Modern electronic devices such as computer systems have not only microprocessor chips, including Intel® i386, i486, Celeron™ or Pentium® processors, but also many other integrated circuits (ICs) and other electronic components, most of which are mounted on printed circuit boards (PCBs). Many of these components generate heat during normal operation. Components that have a relatively small number of functions in relation to their size, as for example individual transistors or small scale integrated circuits (ICs), usually dissipate all their heat without a heatsink. However, more complex components may dissipate an amount of heat which requires the assistance of external cooling devices such as heatsinks.
Heatsinks may be passive devices, for example an extruded aluminum plate with a plurality of fins, that are thermally coupled to a heat source, e.g. an electronic component such as a microprocessor, to absorb heat from the electronic component. The heatsinks dissipate this heat into the air primarily by convection.
Common materials for heatsinks include copper (Cu) or aluminum (Al) based heatsinks with either extruded, folded, or skived fins with no fan or with an active fan to promote airflow efficiency. A retention mechanism such as a clip is sometimes required to secure the heatsink onto an electronic package across the heat dissipation path. An active fan is often mounted on top of the heatsinks to transfer heat, during operation, from a heat source to the ambient air, via the fins.
High power electronic systems such as consumer computer systems or servers may require or benefit from liquid cooling in place of or in addition to other cooling devices. With reference to FIG. 1, a liquid cooled system 10 includes a heat source 11 (e.g. a processor or other electronic device). A cold plate 12 is mechanically and thermally coupled to the heat source 11. The cold plate 12 is in liquid communication with a heat dissipation device 13 (e.g. a condensor and/or radiator). Cooling liquid is circulated from the cold plate 12 to the device 13 and back again to provide a cooling cycle. For example, the cold plate 12 may be connected in a loop to the device 13 by tubing 14. A pump 15 may be provided in line with one branch of the tubing 14 to circulate the cooling liquid contained in the tubing 14 (e.g. in the direction of arrows L). The system 10 may include an optional fan 16 to provide air flow for the heat dissipation device 13 and/or the cold plate 12.
One function of the cold plate 12 is to transfer a heat load from the heat source 11 to the liquid that is circulated through the cold plate 12. Conventional cold plates may be manufactured in low volume by machining out feature details in a piece of metal stock. Higher volume manufacturing techniques such as die casting may also be utilized to manufacture cold plates. However, the higher volume techniques are generally limited in the materials that may be utilized (e.g. lower performance materials such as aluminum, zinc, or magnesium). Also, the higher volume manufacturing techniques are generally limited in terms of the size of the geometries that may be cost effectively made. In particular, smaller geometries are generally more difficult to die cast and/or more expensive to die cast.